Water running through limestone produces unusual cave formations.
Limestone is a type of sedimentary rock made up mostly of calcium. This stone is extremely common in parts oft the world that were once covered by oceans. The skeletons of marine life, including coral, mollusks, sea urchins and fish, fell to the ocean bottom and were covered by sediment. Eventually, the skeletal remnants became high-calcium limestone deposits. Does this Spark an idea?
Content
Any sedimentary rock containing more than 50 percent calcite or dolomite can be considered limestone. This variable composition means that different types of limestone can have very different textures and hardnesses. Some limestone is soft and chalky in texture, while other specimens are filled with fossils, grainy and full of sand, or very hard and made of recrystalized material. Many limestone deposits contain shells and other fossilized animal remains.
Location
Limestone deposits formed all over the world. In the United States, large amounts of this stone appear in Florida, much of the Midwest, the central West and Southwest, and the Appalachians. Limestone deposits can also be found in parts of the British Isles, France, Sweden, Vietnam and China. The famous Niagara Escarpment on the U.S./Canadian border is formed in limestone rock.
Caves
Most caves form in limestone deposits. Acidic rainwater absorbed into the ground reacts with the alkaline limestone bedrock, eating away the calcium. Over time, the water creates a progressively larger space, eventually forming an underground stream. This process can take thousands to millions of years. The result is a system of caverns. Stalactites and stalagmites form from dripping water containing a high percentage of dissolved limestone. This water leaves behind some of the calcium as a deposit, eventually creating these distinctive cave structures.
Considerations
According to Loudon County, Virginia, extensive limestone deposits can adversely affect well water quality, both by increasing mineral content and by allowing easy well contamination. Dissolved limestone can leave calcium deposits on clothing and plumbing fixtures. Water flowing through limestone is also more likely to become contaminated, since surface water easily enters these stone formations. Loudon County recommends that homeowners with wells in limestone test their well water for chemicals, heavy metal and bacterial contamination on a regular basis.
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